A lubrication additive recovery system is provided for use with a vapor compression system. The vapor compression system includes a compressor having a bearing, a condenser and an evaporator. The lubrication additive recovery system includes a lubrication ring formed to define first and second through-holes, a first system by which a portion of a required supply of lubrication is drawn from the condenser and provided to the bearing through the first through-holes and a second system by which a remainder of the required supply of lubrication is recovered from the evaporator and provided along with compressor discharge gas to the bearing through the second through-holes.

A multi-air conditioner for heating/cooling operations, including at least one indoor unit for heating/cooling operations including an indoor heat exchanger; and an outdoor unit for heating/cooling operations including a compressor, an outdoor heat exchanger, and a switching unit configured to be disposed in a discharge side of the compressor to switch a flow of refrigerant. The outdoor unit includes a receiver that selectively stores refrigerant or oil according to a cooling or heating operation mode and provides the stored refrigerant or oil to the compressor. Accordingly, in the accumulator of the multi-air conditioner using the receiver, the receiver which is not used in the heating mode may be converted and used for oil storage, thereby preventing oil burnout without adding structure.

Methods are directed towards dynamically determining refrigerant film thickness at the rolling-element bearing and for dynamically controlling refrigerant film thickness at the rolling-element bearing. Further, an oil free chiller system is configured for dynamically determining refrigerant film thickness at the rolling-element bearing of the oil free chiller system, wherein the oil free chiller system is also configured for dynamically controlling refrigerant film thickness at the rolling-element bearing of the oil free chiller system.

In some embodiments, an air-cooled ammonia refrigeration system comprises: a plurality of air-cooled condensers, each having a heat exchanger and at least one axial fan and having a first operating state capable of condensing vaporous ammonia to form liquid ammonia; an evaporator coupled to the air-cooled condenser; a subcooler positioned between the air-cooled condenser and the evaporator; a compressor coupled to the evaporator; an oil cooler coupled to the compressor; and a plurality of valves coupled to the plurality of air-cooled condensers and having a first configuration corresponding to the first operating state of the plurality of air-cooled condensers, and a second configuration corresponding to a second operating state of one or more of the plurality of air-cooled condensers such that the one or more of the plurality of air-cooled condensers functions as an evaporator capable of evaporating liquid ammonia to form vaporous ammonia.

A control method and system for refrigeration, oil return and noise reduction of a multi-split air-conditioner. The method comprises: when the accumulative time that the frequency of a compressor is smaller than the set frequency threshold reaches the oil return cycle and a standby indoor unit exists, conducting an oil return running mode; resetting the accumulative time;

starting counting the oil return running time; calculating the indoor unit starting load; determining the opening degree of an expansion valve of the standby indoor unit according to the indoor unit starting load and whether there is anyone in a room where the standby indoor unit is located; controlling the compressor to run according to the set oil return frequency; and when the oil return running time reaches the oil return set time, exiting the oil return running mode, and conducting a normal refrigerating running mode. By means of the control method, the oil return effect is ensured, and the influences of throttling sounds caused by opening of the expansion valve of the standby indoor unit on users during oil return are also reduced.

A rotary cylinder piston compressor pump is provided, including a rotating shaft (2), a piston (3) and a cylinder (4). A rotating shaft hole (21) is provided in the rotating shaft (2). An oil guiding channel, provided in the cylinder (4), communicating with the rotating shaft hole (21). A recess (45) is formed in the inner end face of the cylinder (4). An oil path (61) sealed relative to a compression cavity (49) of the cylinder (4) is formed between the recess (45) and the piston (3). The oil path (61) between the recess (45) and the piston (3) is communicated with an oil path (62) between the piston (3) and the rotating shaft (2) and is communicated with the oil guiding channel by means of an oil returning channel. Also provided is a compressor including the compressor pump.

A HVAC system refrigeration circuit is provided. Embodiments of the present disclosure relate to a refrigeration circuit configured to balance the oil carryover between multiple compressors using a single refrigeration circuit. Embodiments of the present disclosure allow for the use of one or more inverter compressors and one or more fixed speed compressors. Embodiments of the present disclosure utilize capillary tubes or other flow control methods to balance the oil carryover between multiple compressors.

An automatic oil level retention system for a compressor and a method for controlling a same, including: a normal oil return mode and an auxiliary oil return mode. When a lubricating oil liquid level monitored by a liquid level detection unit in real time is above a required liquid level height, the system initiates only the normal oil return mode; and when the lubricating oil liquid level monitored by the liquid level detection unit in real time is below the required liquid level height, the system initiates the auxiliary oil return mode, and the auxiliary oil return mode is closed and the normal oil return mode is initiated after the lubricating oil liquid level monitored in real time is lifted above the required liquid level height.

A refrigeration cycle apparatus includes a plurality of outdoor units. Each of the plurality of outdoor units includes an outdoor heat exchanger, a compressor, and a sensor to detect the quantity of refrigeration oil in the outdoor unit. A controller has a first operation mode in which a part of the plurality of outdoor units is operated and another outdoor unit is stopped; and a second operation mode in which all of the plurality of outdoor units are operated. In the first operation mode, when the operating time of an operating outdoor unit exceeds a prescribed time and the quantity of refrigeration oil in the compressor of the operating outdoor unit is equal to or larger than a prescribed quantity, the controller stops the operating outdoor unit and makes a switch to bring a stopped outdoor unit of the plurality of outdoor units into operation.

A mixing device and a vapor compression system incorporating a mixing device are provided. The vapor compression system includes a suction line, at least two compressors, and at least one mixing device that is predominantly open (e.g., i.e., include at least a certain percentage, such as seventy percent (70%), of voids/openings). The suction line is used for transferring a working fluid made up of a mixture of a refrigerant and an oil. The suction line includes at least one inlet (e.g., for receiving the working fluid) and at least one outlet (e.g., for distributing the working fluid). The vapor compression system include a first compressor fluidly connected to a first outlet and a second compressor fluidly connected to a second outlet. At least one mixing device is disposed within the suction line (e.g., to increase an internal turbulence of the working fluid).